筑坐极_mysql学习篇-4

--表结构

--创建表

CREATE TABLE class (

cid int(11) NOT NULL AUTO_INCREMENT,

caption varchar(32) NOT NULL,

PRIMARY KEY (cid)

) ENGINE=InnoDB CHARSET=utf8;

INSERT INTO class VALUES

(1, '三年二班'),

(2, '三年三班'),

(3, '一年二班'),

(4, '二年九班');

CREATE TABLE course(

cid int(11) NOT NULL AUTO_INCREMENT,

cname varchar(32) NOT NULL,

teacher_id int(11) NOT NULL,

PRIMARY KEY (cid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO course VALUES

(1, '生物', 1),

(2, '物理', 2),

(3, '体育', 3),

(4, '美术', 2);

CREATE TABLE score (

sid int(11) NOT NULL AUTO_INCREMENT,

student_id int(11) NOT NULL,

course_id int(11) NOT NULL,

num int(11) NOT NULL,

PRIMARY KEY (sid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

--插入数据

INSERT INTO score VALUES

(1, 1, 1, 10),

(2, 1, 2, 9),

(5, 1, 4, 66),

(6, 2, 1, 8),

(8, 2, 3, 68),

(9, 2, 4, 99),

(10, 3, 1, 77),

(11, 3, 2, 66),

(12, 3, 3, 87),

(13, 3, 4, 99),

(14, 4, 1, 79),

(15, 4, 2, 11),

(16, 4, 3, 67),

(17, 4, 4, 100),

(18, 5, 1, 79),

(19, 5, 2, 11),

(20, 5, 3, 67),

(21, 5, 4, 100),

(22, 6, 1, 9),

(23, 6, 2, 100),

(24, 6, 3, 67),

(25, 6, 4, 100),

(26, 7, 1, 9),

(27, 7, 2, 100),

(28, 7, 3, 67),

(29, 7, 4, 88),

(30, 8, 1, 9),

(31, 8, 2, 100),

(32, 8, 3, 67),

(33, 8, 4, 88),

(34, 9, 1, 91),

(35, 9, 2, 88),

(36, 9, 3, 67),

(37, 9, 4, 22),

(38, 10, 1, 90),

(39, 10, 2, 77),

(40, 10, 3, 43),

(41, 10, 4, 87),

(42, 11, 1, 90),

(43, 11, 2, 77),

(44, 11, 3, 43),

(45, 11, 4, 87),

(46, 12, 1, 90),

(47, 12, 2, 77),

(48, 12, 3, 43),

(49, 12, 4, 87),

(52, 13, 3, 87);

CREATE TABLE student(

sid int(11) NOT NULL AUTO_INCREMENT,

gender char(1) NOT NULL,

class_id int(11) NOT NULL,

sname varchar(32) NOT NULL,

PRIMARY KEY (sid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO student VALUES

(1, '男', 1, '理解'),

(2, '女', 1, '钢蛋'),

(3, '男', 1, '张三'),

(4, '男', 1, '张一'),

(5, '女', 1, '张二'),

(6, '男', 1, '张四'),

(7, '女', 2, '铁锤'),

(8, '男', 2, '李三'),

(9, '男', 2, '李一'),

(10, '女', 2, '李二'),

(11, '男', 2, '李四'),

(12, '女', 3, '如花'),

(13, '男', 3, '刘三'),

(14, '男', 3, '刘一'),

(15, '女', 3, '刘二'),

(16, '男', 3, '刘四');

CREATE TABLE teacher(

tid int(11) NOT NULL AUTO_INCREMENT,

tname varchar(32) NOT NULL,

PRIMARY KEY (tid)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO teacher VALUES

(1, '张磊老师'),

(2, '李平老师'),

(3, '刘海燕老师'),

(4, '朱云海老师'),

(5, '李杰老师');

-- student_id 为分数 id

-- 1、查询所有的课程的名称以及对应的任课老师姓名

select cr.cname,t.tname

from course cr

left join

teacher t on cr.teacher_id = t.tid;

-- 2、查询学生表中男女生各有多少人

select count(gender),gender from student group by gender;

-- 3、查询物理成绩等于100的学生的姓名

select s.sname

from student s

left join score s1 on s.sid = s1.sid

left join

course cr on cr.cid = s1.course_id

where s.cname in (select cname from course where cname = '物理') and

s1.num = 100;

-- 4、查询平均成绩大于八十分的同学的姓名和平均成绩

select se.student_id,st.sname, avg(se.num) as avg_s from score se left join student st on se.student_id = st.sid

group by se.student_id having avg_s > 80;

-- 5、查询所有学生的学号，姓名，选课数，总成绩

select se.student_id,st.sname,count(se.course_id) sc ,sum(se.num) ss from student st left join score se on st.sid = se.student_id group by se.student_id;

-- 6、查询姓李老师的个数

select count(1) from teacher t where t.tname like "李%";

-- 7、查询没有报李平老师课的学生姓名

select st.sname from student st left join score s on st.sid = s.student_id where s.student_id not in(

select distinct se.student_id from score se where se.course_id in (

select ce.cid from course ce where ce.teacher_id =(

select tr.tid from teacher tr where tr.tname = "李平老师")));

-- 8、查询物理课程比生物课程高的学生的学号

select st.sid from student st left join score se on st.sid = se.student_id and se.course_id =

(select ce.cid from course ce where ce.cname = "物理")

left join score se1 on st.sid = se1.student_id and se1.course_id =

(select ce.cid from course ce where ce.cname = "生物")

where se.num > se1.num ;

-- 9、查询没有同时选修物理课程和体育课程的学生姓名

select st.sname from student st left join score se on st.sid = se.student_id and se.course_id = (select ce.cid from course ce where ce.cname ="物理")

left join score se1 on st.sid = se1.student_id and se1.course_id = (select ce.cid from course ce where ce.cname ="体育")

where se.student_id is null and se1.student_id is null ;

-- 10、查询挂科超过两门(包括两门)的学生姓名和班级

select st.sname,cs.caption from student st left join class cs on st.class_id = cs.cid where st.sid in (

select se.student_id from score se where se.num < 60 group by se.student_id having count(1) >=2);

-- 11、查询选修了所有课程的学生姓名

select st.sname from score se left join student st on se.student_id = st.sid group by se.student_id having count(se.course_id) = (select count(1) from course ce);

-- 12、查询李平老师教的课程的所有成绩记录

select * from score se left join student st on se.student_id = st.sid where se.course_id in (

select ce.cid from course ce where ce.teacher_id =(

select t.tid from teacher t where t.tname ="李平老师"));

-- 13、查询全部学生都选修了的课程号和课程名

select ce.cid,ce.cname from score se left join course ce on se.course_id = ce.cid group by ce.cid having count(1) =(

select count(1) from student st );

-- 14、查询每门课程被选修的次数

select se.course_id,count(1) from score se group by se.course_id;

-- 15、查询之选修了一门课程的学生姓名和学号

select st.sid,st.sname from score se left join student st on se.student_id = st.sid group by se.student_id having count(1) = 1;

-- 16、查询所有学生考出的成绩并按从高到低排序（成绩去重）

select distinct se.num from score se order by se.num desc;

select * from score se group by se.num order by se.num desc;

-- 17、查询平均成绩大于85的学生姓名和平均成绩

select st.sname,avg(se.num) as avg_s from student st left join score se on st.sid = se.student_id group by st.sid having avg_s >85;

-- 18、查询生物成绩不及格的学生姓名和对应生物分数

select st.sname,se.course_id, se.num from student st left join score se on st.sid = se.student_id where se.course_id =(

select ce.cid from course ce where ce.cname ="生物") and se.num < 60;

-- 19、查询在所有选修了李平老师课程的学生中，这些课程(李平老师的课程，不是所有课程)平均成绩最高的学生姓名

select se.student_id,st.sname,avg(se.num) avg_s from student st left join score se on st.sid = se.student_id where se.course_id in (

select ce.cid from course ce where ce.teacher_id =(

select tr.tid from teacher tr where tr.tname = "李平老师")) group by se.student_id having avg_s in (select max(avg_s) from

(select se.student_id,st.sname,avg(se.num) avg_s from student st left join score se on st.sid = se.student_id where se.course_id in (

select ce.cid from course ce where ce.teacher_id =(

select tr.tid from teacher tr where tr.tname = "李平老师")) group by se.student_id order by avg_s desc) as t);

-- 20、查询每门课程成绩最好的前两名学生姓名

SELECT sc.course_id,sc.num FROM score sc WHERE (SELECT COUNT(*) FROM score WHERE sc.course_id = score.course_id AND sc.num < score.num)<2 ORDER BY sc.course_id ASC,sc.num DESC;

-- 21、查询没学过“李平”老师课程的学生姓名以及选修的课程名称；

select * from score sr left join student sn on sr.student_id = sn.sid

left join course cs on sr.course_id = cs.cid

where sn.sid not in (select distinct st.sid from student st left join score se on st.sid = se.student_id where se.course_id in (

select ce.cid from course ce where ce.teacher_id = (

select t.tid from teacher t where t.tname = "李平老师")));

-- 22、查询所有选修了学号为1的同学选修过的一门或者多门课程的同学学号和姓名；

select distinct st.sid,st.sname from student st left join score se on st.sid = se.student_id where se.course_id in

(select se.course_id from score se where se.student_id = 01) and st.sid not in (1);

mysql学习篇-4

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mysql学习篇-3

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